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International audience; Recent literature shows that exercise is not simply a way to generate a calorie deficit as an add-on to restrictive diets but exerts powerful additional biological effects via its impact on mitochondrial function, the release of chemical messengers induced by muscular activity, and its ability to reverse epigenetic alterations. This review aims to summarize the current literature dealing with the hypothesis that some of these effects of exercise unexplained by an energy deficit are related to the balance of substrates used as fuel by the exercising muscle. This balance of substrates can be measured with reliable techniques, which provide information about metabolic disturbances associated with sedentarity and obesity, as well as adaptations of fuel metabolism in trained individuals. The exercise intensity that elicits maximal oxidation of lipids, termed LIPOXmax, FATOXmax, or FATmax, provides a marker of the mitochondrial ability to oxidize fatty acids and predicts how much fat will be oxidized over 45–60 min of low- to moderate-intensity training performed at the corresponding intensity. LIPOXmax is a reproducible parameter that can be modified by many physiological and lifestyle influences (exercise, diet, gender, age, hormones such as catecholamines, and the growth hormone-Insulin-like growth factor I axis). Individuals told to select an exercise intensity to maintain for 45 min or more spontaneously select a level close to this intensity. There is increasing evidence that training targeted at this level is efficient for reducing fat mass, sparing muscle mass, increasing the ability to oxidize lipids during exercise, lowering blood pressure and low-grade inflammation, improving insulin secretion and insulin sensitivity, reducing blood glucose and HbA1c in type 2 diabetes, and decreasing the circulating cholesterol level. Training protocols based on this concept are easy to implement and accept in very sedentary patients and have shown an unexpected efficacy over the long term. They also represent a useful add-on to bariatric surgery in order to maintain and improve its weight-lowering effect. Additional studies are required to confirm and more precisely analyze the determinants of LIPOXmax and the long-term effects of training at this level on body composition, metabolism, and health.

The screening of skeletal muscle diseases constitutes an unresolved challenge. Currently, exercise tests or plasmatic tests alone have shown limited performance in the screening of subjects with an increased risk of muscle oxidative metabolism impairment. Intensity-adjusted energy substrate levels of lactate (La), pyruvate (Pyr), β-hydroxybutyrate (BOH) and acetoacetate (AA) during a cardiopulmonary exercise test (CPET) could constitute alternative valid biomarkers to select “at-risk” patients, requiring the gold-standard diagnosis procedure through muscle biopsy. Thus, we aimed to test: (1) the validity of the V’O2-adjusted La, Pyr, BOH and AA during a CPET for the assessment of the muscle oxidative metabolism (exercise and mitochondrial respiration parameters); and (2) the discriminative value of the V’O2-adjusted energy and redox markers, as well as five other V’O2-adjusted TCA cycle-related metabolites, between healthy subjects, subjects with muscle complaints and muscle disease patients. Two hundred and thirty subjects with muscle complaints without diagnosis, nine patients with a diagnosed muscle disease and ten healthy subjects performed a CPET with blood assessments at rest, at the estimated 1st ventilatory threshold and at the maximal intensity. Twelve subjects with muscle complaints presenting a severe alteration of their profile underwent a muscle biopsy. The V’O2-adjusted plasma levels of La, Pyr, BOH and AA, and their respective ratios showed significant correlations with functional and muscle fiber mitochondrial respiration parameters. Differences in exercise V’O2-adjusted La/Pyr, BOH, AA and BOH/AA were observed between healthy subjects, subjects with muscle complaints without diagnosis and muscle disease patients. The energy substrate and redox blood profile of complaining subjects with severe exercise intolerance matched the blood profile of muscle disease patients. Adding five tricarboxylic acid cycle intermediates did not improve the discriminative value of the intensity-adjusted energy and redox markers. The V’O2-adjusted La, Pyr, BOH, AA and their respective ratios constitute valid muscle biomarkers that reveal similar blunted adaptations in muscle disease patients and in subjects with muscle complaints and severe exercise intolerance. A targeted metabolomic approach to improve the screening of “at-risk” patients is discussed.

International audience; Many factors in the surrounding environment have been reported to influence erythrocyte deformability. It is likely that some influences represent reversible changes in erythrocyte rigidity that may be involved in physiological regulation, while others represent the early stages of eryptosis, i.e., the red cell self-programmed death. For example, erythrocyte rigidification during exercise is probably a reversible physiological mechanism, while the alterations of red blood cells (RBCs) observed in pathological conditions (inflammation, type 2 diabetes, and sickle-cell disease) are more likely to lead to eryptosis. The splenic clearance of rigid erythrocytes is the major regulator of RBC deformability. The physicochemical characteristics of the surrounding environment (thermal injury, pH, osmolality, oxidative stress, and plasma protein profile) also play a major role. However, there are many other factors that influence RBC deformability and eryptosis. In this comprehensive review, we discuss the various elements and circulating molecules that might influence RBCs and modify their deformability: purinergic signaling, gasotransmitters such as nitric oxide (NO), divalent cations (magnesium, zinc, and Fe++), lactate, ketone bodies, blood lipids, and several circulating hormones. Meal composition (caloric and carbohydrate intake) also modifies RBC deformability. Therefore, RBC deformability appears to be under the influence of many factors. This suggests that several homeostatic regulatory loops adapt the red cell rigidity to the physiological conditions in order to cope with the need for oxygen or fuel delivery to tissues. Furthermore, many conditions appear to irreversibly damage red cells, resulting in their destruction and removal from the blood. These two categories of modifications to erythrocyte deformability should thus be differentiated.

Resume Introduction et objectif Selon le Centre international de recherche sur le cancer (CIRC) on peut estimer que dans l’Union Europeenne, 13 000 cas de cancer du sein (CDS) pourraient etre evites annuellement par un maintien a la normale du poids corporel. Cette revue a pour objectif d’analyser la relation entre l’Activite physique (AP) et le CDS, cette derniere etant une maladie associee au surpoids et a l’obesite. Actualite L’AP est impliquee dans la relation liant le surpoids et l’obesite au CDS, notamment en ce qui concerne la perte de masse grasse et ses modifications physiologiques : l’AP est susceptible de reguler les dysfonctions au niveau des hormones sexuelles, des hormones regulatrices du metabolisme, au niveau inflammatoire, des adipokines, ainsi que du stress oxydatif. La litterature montre que des AP aerobies, telles que la marche, avec des volumes eleves (e.g. 200–300 min/semaine) et des intensites moderees, ont une efficacite bien etablie.

Background and Purpose: Sleeve gastrectomy is a major therapy of morbid obesity, but recent reports suggest that its effects on weight loss are improved when patients increase their muscular activity, while a weight regain may occur in more than 30% of patients after 40 months. Exercise is an effective mean of preventing weight regain. In a recent preliminary study, we reported that exercise training targeted at the level of maximal lipid oxidation (LIPOXmax) improved weight loss and weight stabilization at 30 months. This study extends this previous one and aims at describing the kinetics of weight loss on 60 months after sleeve in people performing or not a LIPOXmax training and to see whether this variety of training exerts a satietogenic effect in sleeve patientsas has been evidenced in nonoperated obese subjects.

BACKGROUND Obesity is a major public health issue. Combining exercise training, nutrition, and therapeutic education in metabolic rehabilitation (MR) is recommended for obesity management. However, evidence from randomized controlled studies is lacking. In addition, MR is associated with poor patient adherence. Mobile health devices improve access to MR components. OBJECTIVE The aim of this study is to compare the changes in body composition, anthropometric parameters, exercise capacity, and quality of life (QOL) within 12 weeks of patients in the telerehabilitation (TR) program to those of usual care patients with obesity. METHODS This was a parallel-design randomized controlled study. In total, 50 patients with obesity (BMI>30 kg/m²) were included in a TR group (TRG) or a usual care group (UCG) for 12 weeks. Patients underwent biometric impedance analyses, metabolic exercise tests, actimetry, and QOL and satisfaction questionnaires. The primary outcome was the change in fat mass at 12 weeks from baseline. Secondary outcomes were changes in body weight, metabolic parameters, exercise capacity, QOL, patients’ adhesion, and satisfaction. RESULTS A total of 49 patients completed the study. No significant group × time interaction was found for fat mass (TRG: mean 1.7 kg, SD 2.6 kg; UCG: mean 1.2 kg, SD 2.4 kg; P=.48). Compared with the UCG, TRG patients tended to significantly improve their waist to hip ratios (TRG: −0.01 kg, SD 0.04; UCG: +0.01 kg, SD 0.06; P=.07) and improved QOL physical impact (TRG: +21.8, SD 43.6; UCG: −1.2, SD 15.4; P=.005). Significant time effects were observed for body composition, 6-minute walk test distance, exercise metabolism, sedentary time, and QOL. Adherence (95%) and satisfaction in the TRG were good. CONCLUSIONS In adults with obesity, the TR program was not superior to usual care for improving body composition. However, TR was able to deliver full multidisciplinary rehabilitation to patients with obesity and improve some health outcomes. Given the patients’ adherence and satisfaction, pragmatic programs should consider mobile health devices to improve access to MR. Further studies are warranted to further establish the benefits that TR has over usual care. CLINICALTRIAL ClinicalTrials.gov NCT03396666; http://clinicaltrials.gov/ct2/show/NCT03396666

International audience; IntroductionThe main problem in obesity management is weight regain that occurs after all currently used slimming procedures. Regular physical activity remains the most effective measure to stop this weight regain. Among the varieties of training that can be offered, endurance exercise at low to moderate intensities targeted at the level of maximum lipid oxidation (LIPOX max) is one of the easiest to implement and has well-documented effects on glucose metabolism, blood lipids, eating behavior, and body composition. Our purpose in this study was to study the effect of this type of exercise on body composition over 2 years.MethodsNonrandomized controlled longitudinal study. Forty-five obese subjects (14 men, 31 women, age = 20–85 years old) were re-trained with LIPOXmax (3 × 45 min/week at home with regular follow-up after induction in hospital) over 2 years. They were compared to a matched control group of 26 subjects. Exercise calorimetry and segmental bioelectric impedance were performed at the beginning and at the 24th month.ResultsTrained group lost weight (− 6 ± 1.44 kg) over 2 years. This is explained by a loss of fat mass (− 5 ± 1.26 kg), affecting truncal fat mass (− 2.66 ± 0.62 kg P < 0.0001), and appendicular fat mass (1.38 ± 0.72 kg P < 0.01). There is also a reduction in lean body mass (− 2.41 ± 0.86 kg, P < 0.01). Controls gain 3 ± 0.85 kg (P < 0.001). In the trained group, the ability to oxidize lipids increased (P < 0.001) and there was a positive correlation between weight changes and mean arterial blood pressure at 24 months (R = 0.37 P = 0.02).ConclusionThe weight loss effectiveness of endurance training targeted at the LIPOXmax is maintained for 24 months. This weight loss affects both trunk and appendicular fat mass but also lean mass. It associated with a decrease in blood pressure and an improvement in the ability to oxidize lipids during exercise.; IntroductionLe grand problème de l’obésité est la reprise pondérale qui peut s’observer après toutes les thérapeutiques actuellement utilisées. L’activité physique régulière reste la mesure la plus efficace permettant d’enrayer cette reprise de poids. Parmi les types d’entraînement proposés, l’endurance à des intensités faibles à modérées ciblée sur le niveau d’oxydation lipidique maximale (LIPOX max) est une des plus faciles à mettre en œuvre et a des effets bien documentés sur le métabolisme gluco-lipidique, le comportement alimentaire, et la composition corporelle. Nos objectifs dans cette étude ont été d’étudier l’effet de ce type d’exercice sur la composition corporelle sur 2 ans.MéthodesÉtude longitudinale contrôlée non randomisée. Quarante-cinq sujets obèses (14 hommes, 31 femmes, âge = 20–85 ans) ont été réentraînés au LIPOXmax (3 × 45 min/semaine à la maison avec suivi régulier, après induction en milieu hospitalier) sur 2 ans. Ils ont été comparés à un groupe témoin apparié de 26 sujets. La calorimétrie d’exercice et l’impédance bioélectrique segmentaire ont été réalisées au début et au 24e mois.RésultatsLe groupe réentraîné a perdu du poids (− 6 ± 1,44 kg) sur 2 ans et − 6 ± 2,2 kg après 5 ans. Cela s’explique par une perte de masse grasse (− 5 ± 1,26 kg), affectant la masse grasse tronculaire (− 2,66 ± 0,62 kg p < 0,0001), et la masse grasse appendiculaire (1,38 ± 0,72 kg p < 0,01). Il y a aussi une réduction de masse maigre (− 2,41 ± 0,86 kg, p < 0,01). Les contrôles gagnent 3 ± 0,85 kg (p < 0,001). Dans le groupe réentraîné, la capacité à oxyder les lipides a augmenté (p < 0,001) et on retrouve une corrélation positive entre les changements de poids et la pression artérielle moyenne à 24 mois (r = 0,37 p = 0,02).ConclusionL’efficacité amaigrissante de l’entraînement en endurance au LIPOX Max est maintenue à 24 mois et l’on observe que cette perte de poids affecte la masse grasse tronculaire et appendiculaire mais aussi la masse maigre et s’accompagne d’une diminution de la pression artérielle et d’une amélioration de la capacité à oxyder les lipides à l’exercice.

International audience; Hematocrit increases during exercise and is usually decreased after regular training. However the interpretation of these facts is ambiguous since hematocrit is both a determinant of oxygen supply and the major determinant of blood viscosity. Classically hematocrit was assumed to impair blood flow, but it has been evidenced to exert a biphasic effect on it. In order to cope with these two apparently opposite effects of hematocrit, hemorheologists have proposed the concept hematocrit/viscosity ratio (h/η). This h/η ratio is related to tissue oxygenation in vascular diseases (eg, POAD) but not in healthy subjects. h/η displays a bell-shaped curve as a function of hematocrit and the hematocrit value corresponding to the maximal h/η can be assumed to be a theoretically optimal hematocrit. We propose to analyse exercise-related alterations in hematocrit according to this theoretical approach, viscosity at high shear rate being reconstructed with Quemada's equation from actual plasma viscosity and red cell rigidity at various hematocrit levels. While theoretical and actual h/η are fairly correlated in athletes both before and after exercise, actual hematocrit is lower at rest and higher after exercise compared to the theoretical one. The main statistic correlate of these discrepancies between actual and predicted hematocrit is red cell rigidity. Submaximal exercise acutely decreases the h/η ratio (despite increasing both hematocrit and viscosity). This change is well predicted by the model and there is a strong correlation between predicted and actual h/η ratio. Endurance training tends to increase h/η and to reduce the discrepancy between predicted and actual hematocrit. Accordingly trained athletes have a higher h/η (both model-predicted and actual) than sedentary subjects, and a lower hematocrit, this lowering being rather correlated to training volume than to fitness improvement. On the whole, this approach suggests that homeostatic "viscoregulation" in athletes results in a fine tuning of h/η which seems to be a closely regulated parameter. Hematocrit alterations in this context are an adaptation involved in this regulation.

Subjects with hypothyroidism substituted with levothyroxine (HS) are known to be poor responders to weight reducing strategies. Since muscle energy metabolism is regulated by thyroid hormones we compared the oxidation of fat and carbohydrates (CHO) during exercise in HS versus controls. We compared 52 patients (48 women, 4 men, age 49 t years, levothyroxine dose 25-250 micrograms / day) to a control group of 2081 patients matched for sex, age, BMI and percentage of fat during an exercise calorimetry with 4 submaximal 6 minutes steps. At the same power intensity HS on the average oxidize more fat (p = 0.009) and use more oxygen (p = 0.00019). Lipid oxidation culminates at the same power intensity(39,4±2,4 vs 38,6±0,3 watts) but its maximal oxidation rate is significantly higher in the HS group (10.32±0.47 vs. 9, 06±0.10 mg / min / kg muscle p = 0.02) and carbohydrate oxidation during the final level (1866.6 ± 77.3 vs1705.45 ± 11.5 mg / min p = 0.029 ). The maximal lipid oxidation rate is correlated with the dose of levothyroxine (r = 0.331, p

Resume L’activite physique (AP) est un element tres important de la prise en charge du cancer du sein (CDS) en complement de l’approche carcinologique. Elle diminue la mortalite, toutes causes confondues, de ces patientes. L’AP moderee s’est averee tout particulierement interessante dans ce contexte, ce qui peut suggerer que le ciblage au LIPOXmax peut trouver une indication dans ce contexte. Nous avons donc voulu determiner le profil d’oxydation des lipides et des glucides a l’exercice chez ces patientes. Quinze patientes (âge 56,8 ± 1,8 ; IMC 32,7 ± 1,3 kg/m2) realisent une calorimetrie d’effort et sont comparees a 182 femmes temoins appariees pour l’âge et l’anthropometrie. Les patientes ont une aptitude aerobie plus basse de −12 % (p = 0,01) leur LIPOXmax survient a une puissance plus basse (p = 0,01), de meme que leur point de croisement (p = 0,01) et le niveau ou les glucides deviennent le substrat exclusif (p = 0,009). Le cout glucidique du watt, qui quantifie la relation lineaire entre l’oxydation des glucides et la puissance, est egalement plus eleve chez les patientes (0,32 ± 0,03 vs. 0,26 ± 0,02 mg/min/kg/watt ; p = 0,02). Ces donnees montrent que les patientes, pour des raisons probablement liees a la fois au terrain predisposant (adiposite et sedentarite) et au parcours therapeutique (inflammation de bas grade, fonte musculaire, deconditionnement a l’exercice) ont un profil de calorimetrie d’effort caracterise par une utilisation majoritaire des glucides et une faible utilisation des lipides, plus encore que des patientes appariees pour l’âge et la corpulence. Il reste a determiner si un reentrainement cible au LIPOXmax, facile a mettre en place chez ces patientes souvent astheniques, reequilibre ce profil et ameliore la composition corporelle et l’inflammation de bas grade comme montre dans d’autres populations.

Resume Actualites La chirurgie bariatrique a pris une place importante dans le traitement de l’obesite mais son efficacite a long terme est compromise dans 20–30 % des cas par des reprises de poids. L’activite physique pourrait etre une strategie preventive et/ou curative de ces echecs secondaires. Nous presentons une revue generale des etudes portant sur l’activite physique apres chirurgie bariatrique. Pour cela, nous avons selectionne 11 articles ayant etudie l’effet d’un protocole d’activite physique postoperatoire. De maniere globale, l’activite physique a des effets positifs sur le systeme cardiovasculaire, le maintien de la capacite fonctionnelle et musculaire, l’insulino-sensibilite et le metabolisme des lipides. Les effets sur le poids sont un peu discordants mais les protocoles realises apres la phase initiale de perte de poids rapide et sur une duree suffisante retrouvent perte de poids superieure a celle qu’induit la chirurgie bariatrique seule. Cet effet renforcant celui de la chirurgie sur la perte de poids est observe avec l’activite en endurance a faible intensite et notamment celle qui est ciblee au LIPOXmax, et n’est pas retrouvee avec l’endurance a plus haute intensite ou la resistance. Conclusion En resume, l’ensemble des articles presentes montrent des effets benefiques sur les comorbidites et complications de l’obesite. Cependant, les protocoles d’entrainement sont heterogenes entre les etudes. Des etudes complementaires sont necessaires afin de mieux preciser les strategies les plus adaptees.

Introduction et but de l’etude L’obstacle majeur dans la prise en charge de l’obesite est la recidive ponderale. L’activite physique est une strategie bien reconnue pour prevenir cette recidive. Parmi les varietes d’entrainement proposees, l’endurance ciblee a une intensite faible a moderee au niveau de l’oxydation lipidique maximale (LIPOX max) a des effets prolonges de reduction de la masse grasse et ameliore le metabolisme glucido-lipidique, la pression arterielle et le comportement alimentaire. Notre objectif dans ce travail etait de determiner dans quelle mesure ces effets sont retrouves de facon prolongee a 6 ans. Materiel et methodes Au total, 343 sujets obeses ont ete entraines au LIPOXmax (3 × 45 min/semaine a domicile avec un suivi regulier, apres induction dans notre unite hospitaliere). Sur ce nombre les donnees de 15 sujets qui ont continue a etre suivis pendant 6 ans (14 hommes, 31 femmes, âge = 20–85 ans) sont desormais disponibles. Des tests de calorimetrie et d’impedance bioelectrique segmentaire ont ete realises avant le debut du reentrainement et au 72e mois. Resultats et analyse statistique Les sujets entraines ont perdu du poids (−6,69 ± 1,4 kg p Conclusion L’efficacite amaigrissante precedemment demontree de l’entrainement d’endurance au LIPOX max se prolonge encore a 6 ans. On observe une diminution de la masse grasse avec une amelioration parallele de l’aptitude maximale aerobie et de la capacite a oxyder les lipides a l’exercice. L’amelioration du profil tensionnel observee a 4 ans semble se retrouver a 6 ans, ce qu’il faudra confirmer sur un echantillon plus etoffe. Ce protocole d’entrainement bien tolere et tres facile a gerer s’avere donc efficace a long terme pour corriger le surpoids et ameliorer la composition corporelle. Ses effets benefiques sur le plan metabolique et circulatoire demontres sur des periodes plus courtes [1] , [2] necessiteront des etudes complementaires pour voir dans quelle mesure ils persistent a 6 ans.

La modelisation mathematique des repas test quantifie les deux phases de l’insulinosecretion ainsi qu’un parametre appele potentiation qui indique que la reponse insulinosecretrice s’amplifie lorsque le stimulus glucose persiste. Nous avons examine si cette potentiation est associee a la survenue d’hypoglycemies reactionnelles sur une base de donnees de 620 petits dejeuners standardises realises pour caracterisation d’anomalies de la glucoregulation avec analyse mathematique de l’insulinosecretion et de ses composantes (modeles de Mari et de Cobelli) ainsi que de l’insulinosensibilite (SI) avec l’oral minimal model. Le quartile superieur de potentiation correspond a des nadirs de glycemie 2 fois plus souvent

Introduction et but de l’etude Le grand probleme de l’obesite est la reprise ponderale qui peut s’observer apres toutes les therapeutiques actuellement utilisees. L’activite physique reguliere reste la mesure la plus efficace permettant d’enrayer cette reprise de poids. Parmi les types d’entrainement proposes, l’endurance a des intensites faibles a moderees ciblee sur le niveau d’oxydation lipidique maximale (LIPOX max) est une des plus faciles a mettre en œuvre et a des effets bien documentes sur le metabolisme gluco-lipidique, le comportement alimentaire, et la composition corporelle. Nos objectifs dans cette etude ont ete d’etudier l’effet de ce type d’exercice sur la composition corporelle sur 2 ans, avec un suivi prolonge sur 5 ans. Materiel et methodes Etude longitudinale controlee non randomisee. 45 sujets obeses (14 hommes, 31 femmes, âge = 20–85 ans) ont ete reentraines au LIPOXmax (3 × 45 min/semaine a la maison avec suivi regulier, apres l’induction en milieu hospitalier) sur 2 ans. Ils ont ete compares a un groupe temoin apparie de 26 sujets. La calorimetrie d’exercice et l’impedance bioelectrique segmentaire ont ete realisees au debut et au 2e mois. Le suivi a ete prolonge sur 5 ans et les resultats ont ete disponibles pour 8 sujets par rapport a un groupe temoin de 11 sujets. Resultats et analyse statistique Le groupe reentraine a perdu du poids (−6 ± 1,44 kg) sur 2 ans et −6 ± 2,2 kg apres 5 ans. Cela s’explique par une perte de masse grasse (−5 ± 1,26 kg), affectant la masse grasse tronculaire (−2,66 ± 0,62 kg p Conclusion L’efficacite amaigrissante de l’entrainement en endurance au LIPOX Max est maintenue sur une periode d’au moins 5 ans. A 24 mois on observe que cette perte de poids affecte la masse grasse tronculaire et appendiculaire mais aussi la masse maigre et s’accompagne d’une diminution de la pression arterielle et d’une amelioration de la capacite a oxyder les lipides a l’exercice.

International audience; Objective: Six- minutes’ walk-test (6MWT) is a measure of physical fitness widely studied and validated in chronic pathologies with sedentary lifestyles. It is an aerobic fitness test, correlated with maximum oxygen consumption (VO2max) in some studies, but this correlation is not well established in diabetes. We assessed the extent to which it predicts VO2max and its training-induced changes in type 2 diabetics.Materials and methods: Twenty-five type 2 diabetics were randomized and divided into two groups: 13 completed a physical training program (eight hospital education sessions continued at home through two weekly 30-45-minute sessions at an intensity corresponding to the first ventilatory threshold VT1) and the remaining 12 continued their usual treatment unchanged.Results: After 1 year training maintained maximum aerobic capacity, while it decreased significantly in the untrained group (p=0.014). Voorrips’ activity score was correlated with VO2max (r= 0.44, p= 0.05) and with the distance walked at 6MWT (r=0.446, p=0.05). The distance walked during 6MWT is correlated with VO2max before (r= 0.456 p= 0.05) and after (r= 0.714 p

The ideal hematocrit is the hematocrit (Hct) value resulting in the highest value of Hct/viscosity (h/η) ratio and can thus be predicted from viscometric measurements with the use of equations such as Quemada's one which yield the determination of the bell-shaped curve of h/η as a function of Hct. In a series of recent papers we applied this approach to various populations, using viscometry at high shear rate (1000 s-1). However the shape of this curve has been reported to be dependent on the shear rate, resulting in a right-shift in this top value when Hct increase. We present here in 11 young recreative athletes the evolution of the predicted top of the h/η curve and optimal theoretical Hct and the discrepancy between theoretical and optimal values over the range of shear rates 1 to 6000 s-1. Results show that the predicted optimal value of both h/η and Hct increases when shear rate increases and that the discrepancy between predicted laquooptimalraquo and actual values decreases and becomes almost asymptotic at very high shear (500 s-1). It is minimal at 2720 s-1. The correlation between predicted laquooptimalraquo and actual values of both parameters describes the same evolution. Therefore, it is better for assessing h/η and its agreement with theoretical values, and for determining the theoretical ideal hematocrit, to measure blood viscosity at shear rates equal or superior to 500 s-1.

We previously reported that whole body bioelectrical impedance analysis (BIA) measurements are correlated to some hemorheologic factors, suggesting a relationship between viscosity factors and electric properties of flowing blood not only in vitro but also in vivo. Recently we reported that with segmental BIA (analyzing the body considered as composed of 5 cylinders) predictive equations for various determinants of blood viscosity were closer than for the wole body. Another widely used BIA technique uses leg-to-leg impedance measurements so that two cylinders (the two legs) are analyzed. We investigated whether impedance measured with this technique (Tanita TBF-300) is also a predictor of blood viscosity factors. From viscometric measurements performed on venous blood drawn in recreative athletes over the range of shear rates 1 to 6000 s-1 (RHEOMETRE Anton Paar CP 50-1), we found a correlation between leg-leg resistance at 50 kHz (Rx[50 kHz]) and blood viscosity at 1000 s-1 (η1000= 0.0051 Rx[50 kHz] + 1.3265; r = 0.521 p = 0.028 yielding a prediction of η1000 (Bland Altman plot: bias 0.05 [RANGE - 0.24; 0.34]. Neither plasma viscosity nor the red cell rheology index «k» of Quemada's model are correlated with Rx[50 kHz], but hematocrit (Hct) does (Hct (%) = 0.0217 Rx[50 kHz] + 33.783; r = 0.480 p = 0.044) yielding a prediction of Hct (Bland Altman plot: bias - 0.11, [range - 1.67; 1.45]. The discrepancy between actual and predicted Hct is also correlated with resistance at 50 kHz (r = 0.575 p = 0.031) as does the discrepancy between actual and predicted Hct/viscosity ratio (r = -0.651 p = 0.006). Therefore, as other previously studied methods, leg to leg BIA predicts viscosity, suggesting that blood rheology may influence the passage of an electric current in the legs.

Physiological modifications of blood rheology during pregnancy and their alterations in pregnant hypertensive women have been extensively studied in the 1980's. Since vascular resistance is higher in hypertensive pregnant women whose newborns are small-for gestational-age (SGA), we investigated in a personal database if growth retardation of newborns is related to the oxygen delivery index (ratio hematocrit/blood viscosity) and to the difference between hematocrit (Hct) and the prediction of its optimal valued based on Quemada's equation. A sample of 38 hypertensive pregnant women (age 29 yr±1) was compared with 64 controls matched for age and gestational age, studied at 35±1 weeks gestation, extracted from a larger series of 162 pregnant women. On the whole the hypertensive group gave birth to smaller children (p = 0.014). Plasma viscosity correlated with blood pressure (BP) only in hypertensive women (r = 0.403 p < 0.05). The bell-shaped curve of predicted optimal Hct of non hypertensive pregnant women was similar to that of non-pregnant women, but in hypertensive women it was shifted toward higher values (p = 0.07), and the predicted optimal Hct (but not the actual one) was correlated with systolic blood pressure (SBP) (r = 0.349 p < 0.001) and diastolic blood pressure (DBP) (r = 0.218 p < 0.05). The predicted optimal Hct/viscosity (h/η) ratio was higher in hypertensive women whose newborns exhibited a low birth weight (p = 0.03), resulting in a higher discrepancy between actual and model-predicted «ideal» values of h/η ratio (p = 0.03) and Hct (p = 0.02) compared with the subgroup with no growth retardation. Therefore, in hypertensive women whose newborns exhibited a low birth weight, hemorheological parameters predicting oxygen supply are shifted to lower values than predicted by the model.

18 healthy untrained children (13 boys, 5 girls) performed a 15 min submaximal incremental exercise on cycloergometer rising heart rate (HR) up to a final step (5 min) at 90% of theoretical maximal heart rate

Resume Introduction Dans la prise en charge de l’obesite, de grandes etudes recentes ont precise l’efficacite de differents regimes utilisables a long terme, dont celui moderement enrichi en proteines. Or ce regime augmente l’oxydation des lipides a l’exercice, ce qui pose la question d’une synergie amaigrissante de l’exercice cible sur l’oxydation des lipides et de l’enrichissement de la ration en proteines. Materiels et methodes Afin de comprendre si l’activite physique en endurance a faible intensite agit en synergie avec l’enrichissement modere de la ration en proteines, nous avons compare les pertes de poids obtenues en soumettant une population de femmes obeses resistantes a l’amaigrissement, a trois strategies differentes pendant un an : reentrainement cible sur l’oxydation des lipides, enrichissement en proteines purifiees de blanc d’œuf (lovamine) et association des deux demarches. Resultats Les sujets LIPOXmax ont perdu 3,93 ± 0,33 kg (3,57 % de leur poids initial) en moyenne et ceux qui prenaient seulement la supplementation moderee en proteines ont perdu en moyenne 3,54 ± 0,17 kg, soit 4,92 % de leur poids initial. Cette difference n’est pas significative, les pertes de poids sous LIPOXmax seul ou enrichissement modere en proteines seul sont similaires ( p = 0,05). Ceux associant LIPOXmax avec un supplement de proteines ont perdu 6,17 ± 0,34 kg, soit 8,18 % de leur poids initial en moyenne. La difference de perte de poids entre les sujets simplement reentraines au LIPOXmax et les sujets reentraines au LIPOXmax et recevant une supplementation moderee en proteines est significative ( p = 0,026). Conclusion Ce travail montre que la supplementation en proteines de blanc d’œuf semble etre un complement interessant a l’activite physique en endurance douce ciblee sur l’oxydation des lipides.

Background After Roux-en-Y gastric bypass (RYGB), hypoglycemia can occur and be associated with adverse events such as intense malaise and impaired quality of life. Objective To compare insulin secretion, sensitivity, and clearance between two groups of patients, with or without hypoglycemia, after an oral glucose tolerance test (OGTT 75-g), and also to compare real-life glucose profiles within these two groups. Setting Bariatric surgery referral center. Methods This study involves a prospective cohort of 46 consecutive patients who complained of malaise compatible with hypoglycemia after RYGB, in whom an OGTT 75-g was performed. A plasma glucose value of lower than 2.8 mmol/L (50 mg/dl) between 90 and 120 min after the load was considered to be a significant hypoglycemia. The main outcome measures were insulin sensitivity, beta-cell function, and glycemic profiles during the test. Glucose parameters were also evaluated by continuous glucose monitoring (CGM) in a real-life setting in 43 patients. Results Twenty-five patients had plasma glucose that was lower than 2.8 mmol/L between 90 and 120 from the load (HYPO group). Twenty-one had plasma glucose that was higher than 2.8 mmol/L (NONHYPO group). The HYPO patients were younger, had lost more weight after RYGB, were less frequently diabetic before surgery, and displayed higher early insulin secretion rates compared with the NONHYPO patients after the 75-g OGTT, and they had lower late insulin secretion rates. The HYPO patients had lower interstitial glucose values in real life, which suggests that a continuum exists between observations with an oral glucose load and real-life interstitial glucose concentrations. Conclusions This study suggests that HYPO patients after RYGB display an early increased insulin secretion rate when tested with an OGTT. CGM shows that HYPO patients spend more time below 3.3 mmol/L when compared with NONHYPO patients. This phenotype of patients should be monitored carefully after RYGB.

Introduction et but de l’etude L’oxydation lipidique presente une courbe en forme de cloche en fonction de l’intensite de l’exercice. Des travaux anciens montraient que cette courbe etait influencee par le poids corporel, le sexe et l’âge. Cependant, des travaux tout recents remettent en question ces donnees classiques. Nous avons l’occasion unique de reevaluer toutes ces relations sur une importante base de donnees de plus de 5000 calorimetries d’effort. Materiel et methodes Notre base de donnees comprend 5258 calorimetries (3618 femmes et 1640 hommes) effectuees en milieu hospitalier pour cibler l’entrainement. La mesure de l’oxydation des lipides et des glucides est effectuee au cours d’un test d’exercice sous-maximal avec quatre paliers de 6 min permettant d’atteindre un etat stable d’echanges gazeux. Les courbes d’oxydation lipidique en fonction de l’intensite de l’exercice ont ete comparees selon le sexe, l’indice de masse corporelle IMC et l’âge. Resultats et analyse statistique En moyenne, le point d’oxydation maximale des lipides est retrouve a 47 ± 1 % de VO2max. A ce niveau, les sujets oxydent 209,5 ± 1,37 mg/min de lipides. L’oxydation maximale des lipides corrigee pour le poids est significativement decalee a droite de 8 a 15 % chez les femmes comparativement aux hommes (p = 0,05). Lorsque l’oxydation des lipides est rapportee a la masse musculaire les femmes oxydent davantage de lipides (+ 10 a 21 %) que les hommes (p = 0,025). L’oxydation des lipides durant l’exercice diminue significativement avec l’âge (p Conclusion Cette etude montre sur une vaste base de donnees que la capacite d’oxyder les lipides a l’exercice est legerement plus elevee en moyenne chez les femmes, et est diminuee avec l’obesite et le vieillissement.

Rheological properties of plasma and blood cells are markedly influenced by the surrounding milieu: physicochemical factors, metabolism and hormones. Acid/base status, osmolality, lipid status, plasma protein pattern, oxidative stress induced by increased free radicals production, endothelium-derived factors such as nitric oxide (NO), achidonic acid derivatives modulate both red blood cell (RBC) and white cell mechanics. Therefore, regulatory axes involving liver, endothelium, kidney, pancreas, adrenal gland, endocrine heart, adipose tissue, pituitary gland, and surely other tissues play important roles in the regulation of blood fluidity. A comprehensive picture of all this complex network of regulatory loops is still unavailable but current progress of knowledge suggest that some attempts can currently be made.

Discipline Clinique. Introduction et but de l’etude L’activite physique, puissant insulino-sensibilisateur, est desormais reconnue comme l’un des outils therapeutiques du diabete. Le reentrainement en endurance de faible intensite cible au LIPOXmax a montre son efficacite sur l’equilibre glycemique notamment dans l’essai randomise “LIPOXmax Reunion”. On sait par ailleurs qu’il permet une perte de poids prolongee dans l’obesite. La perte de poids est egalement un objectif important dans le diabete de type 2 (DT2) et est souvent particulierement difficile a obtenir. Nous avons donc suivi un groupe de DT2 sur 36 mois pour evaluer l’efficacite sur le poids de cette demarche sur 3 ans. Materiel et methodes 16 DT2 traites par le traitement routinier actuel (ADO, GLP1 analogues et analogues d’insuline) âges de 40–71 ans compares a 287 temoins apparies pour la corpulence l’âge et le sexe. Apres calorimetrie d’effort les sujets realisent 8 seances d’induction de reentrainement en milieu hospitalier pour mettre en place dans leur vie quotidienne une activite ciblee au LIPOXmax, 3 × 45 minutes par semaine. Ils sont suivis en consultation au long cours. Resultats et analyse statistique Les deux courbes de perte de poids sont superposees jusqu’a 6 mois puis se separent de plus en plus (p Conclusion Ces resultats confirment qu’il reste plus difficile de faire maigrir des DT2 que des non diabetiques avec l’exercice physique, meme avec une demarche douce et facile a mettre en œuvre comme le LIPOXmax, et ce d’autant plus que les patients sont traites par insulinotherapie et/ou sulfonylurees (ce qui s’accompagne d’une moindre utilisation oxydative des lipides a l’exercice). La baisse d’HbA1c de 0,6 % est evidemment plurifactorielle dans cette etude de suivi de « vraie vie » mais concorde avec les donnees d’etudes interventionnelles demontrant une efficacite interessante de l’exercice en endurance de faible intensite sur l’equilibre glycemique.

Discipline Clinique. Introduction et but de l’etude L’obesite est devenue un grave probleme de sante publique, elle atteint maintenant tous les âges et, en particulier, les personnes âgees. Elle cause plusieurs problemes metaboliques, l’un d’eux, la resistance a l’insuline. L’objectif de l’etude est de determiner l’effet de l’entrainement en resistance sur la sensibilite a l’insuline. Materiel et methodes La population de cette etude se compose de 31 femmes sedentaires, post-menopausees, obeses et saines (âge : 63,81 ± 3,12 ; IMC : 34,17 ± 3,65). Dix-neuf d’entre elles (Groupe ER) ont realise un entrainement de renforcement musculaire en resistance pendant 16 semaines et 12 ont servi de groupe temoin (Groupe C). Un test d’hyperglycemie provoquee par voie orale (HGPO) a ete realise pour mesurer la sensibilite a l’insuline. Ensuite en utilisant les equations de l’oral minimal model, on a pu calculer l’insulino-sensibilite (SI) et classer le groupe ER en 2 sous-groupes : insulino-resistant [ER-IR, SI 6,3 min−1/(μU/ml) .10−4]. Des mesures de la composition corporelle (masse maigre, masse grasse, masse osseuse, masse grasse visceral), des caracteristiques metaboliques (pression arterielle, glycemie, insulinemie, HOMA-IR, triglycerides, HDL, LDL, ApoB, CRP, cholesterol total) et caracteristiques physiques (force de prehension, force musculaire (1RM) et VO2max) ont ete effectuees. Resultats et analyse statistique L’intervention en renforcement musculaire de 16 semaines n’a induit aucun effet sur la composition corporelle, la pression arterielle, la glycemie, l’insulinemie, les triglycerides, HDL, LDL, ApoB, CRP et le cholesterol total. Apres cette intervention on a observe chez le groupe ER une baisse de l’indice simplifie de la resistance a l’insuline (HOMA-IR, p Conclusion Ce protocole d’entrainement en resistance ameliore la force musculaire et plusieurs indices de glycoregulation chez des femmes âgees, obeses et insulino-resistantes.

Resume Introduction L’exercice physique a un effet satietogene et un effet orexigene, ce dernier semblant favorise par la depletion glycogenique et les exercices a haute intensite. L’equilibre entre ces deux effets semble determiner fortement l’effet de l’activite musculaire sur l’adiposite. Notre hypothese est que l’efficacite du reentrainement au LIPOXmax s’expliquerait partiellement par une modulation du comportement alimentaire. L’effet chronique de l’entrainement cible au LIPOXmax a ete etudie chez 25 sujets en surpoids (IMC ≥ 25 kg/m 2 ) et obeses (IMC ≥ 30 kg/m 2 ) dont 21 femmes et 4 hommes. Dans l’ensemble les 25 sujets ont maigri : –2,05 ± 0,8 kg ; p p p p p p p p p p p p p p r = 0,634, p = 0,003). Ce travail montre donc que l’entrainement au LIPOXmax des sujets obeses augmente la sensation de satiete au repos, diminue progressivement l’effet orexigene d’une seance isolee, et diminue la consommation calorique et le grignotage correlativement a une diminution des pensees dirigees vers la nourriture, determinant une perte de poids chez 72 % des sujets. L’effet amaigrissant du reentrainement au LIPOXmax semble donc s’expliquer au moins en partie par une augmentation de l’effet satietogene et une diminution de l’effet orexigene de l’exercice, entrainant une modification mesurable de la prise alimentaire. Ces resultats mettent ainsi en evidence un nouveau mecanisme qui renforce l’interet de ce type de reentrainement dans la prise en charge de l’obesite.

Resume Introduction Le LIPOX max est le niveau d’exercice spontanement selectionne pour un exercice prolonge. Synthese des faits Nous proposons l’hypothese suivante : ce fait resulte de ses proprietes energetiques « economes » : economie de glucides, utilisation des reserves quasi inepuisables de lipides, diminution des pulsions orexigenes. Ce niveau d’exercice etait probablement utilise plusieurs heures par jour par les chasseurs-cueilleurs du paleolithique superieur chez lesquels s’est selectionne durant des millenaires l’ensemble de polymorphismes genetiques codant pour le « genotype econome ». Ces chasseurs-cueilleurs se nourrissaient principalement de viandes maigres et de vegetaux sauvages (alimentation riche en proteines et glucides a faible index glycemique, pauvre en lipides). La sedentarite determine chez les patients caracterises par ces genotypes un stockage de lipides ameliorant la capacite a survivre a une immobilisation d’origine traumatique ou infectieuse (paradoxe de l’obesite), mais pathogene a long terme. Les etats affutes correspondant au sport de haut niveau etaient energetiquement couteux et reserves a une elite du groupe. Ils s’accompagnent d’une reduction tres marquee de la masse grasse. Entre ces deux extremes l’exercice au LIPOX max pratique regulierement par la majorite des individus permettait de tirer le meilleur parti du genotype econome, moderant la prise alimentaire, les fringales hypoglycemiques, et la masse grasse. L’alimentation raisonnablement riche en protides et en sucres lents renforce cette strategie en augmentant l’oxydation des lipides a l’exercice. Conclusion Ce modele que nous proposons expliquerait l’interet dans le syndrome metabolique de l’exercice au LIPOX max associe a une alimentation discretement enrichie en protides (1,2 g/kg/j) et en glucides lents et pauvre en lipides, ces modalites d’exercice et de nutrition etant adaptees au « genotype econome » herite de nos ancetres paleolithiques, du fait de leurs effets sur le metabolisme energetique et le comportement alimentaire.

Context Islet transplantation (IT) can treat patients with severely unstable type 1 diabetes. Prehepatic kinetics of insulin secretion (ISec) in two phases can be calculated by C-peptide levels during meal tests. We proposed to describe the ISec profile after a mixed-meal tolerance test (MMTT) in IT recipients and to determine whether the calculated ISec indexes can predict graft outcome. Methods We analyzed 34 MMTT among 11 patients who underwent IT between 2011 and 2016 and compared them with healthy controls and patients with type 2 diabetes (T2D). ISec indexes and insulin sensitivity were calculated from models of Van Cauter, Breda, and Mari after MMTT. Graft success was defined by total insulin independence without any criteria for diabetes. Results In patients with successful IT, the first- and second-phase ISec indexes were lower than those of controls (P < 0.001) and did not differ from those of the T2D group. Nevertheless, insulin sensitivity of IT recipients was similar to that of the control group and higher than that of the T2D group. The index of the second phase of ISec ɸS was correlated with total infused islet equivalents (IEQs), was a good predictor of diabetes (re)occurrence, and allowed us to calculate 9500 IEQ/kg as the minimum needed to reach insulin independence. Conclusion We showed that indexes from the first and second phases of ISec are altered in insulin-independent IT recipients. Higher sensitivity distinguishes them from patients with T2D. Even in insulin-independent patients, IT remains a marginal mass model. Moreover, ɸS can estimate transplanted islet mass and predict IT recipient outcomes.

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International audience; Among various strategies of exercise intensification proposed for the management of obesity and type 2 diabetes, endurance training remains a well recognized procedure. When targeted with exercise calorimetry at levels where lipid oxidation is maximal (LIPOXmax), it has been shown to improve mitochondrial respiration, blood glucose control and blood lipids, low grade inflammation and body composition, even at low weekly volume. We investigated in this study its long term effects over 3 years (3x45 min/week) compared to low fat diet without exercise (LFD) and a control group without any exercise or diet (C). 88 subjects that continued LIPOXmax training more than 1 year (23 men, 65 women, age=20-85 years, body mass index =23-48 kg/m2) were compared to two matched groups (C and LFD). While C gained weight over this period, LFD and LIPOXmax group lose weight. Weight loss at 1 year was the same in exercise and diet group, but at 2 years and even more at 3 years there was a gradual weight regain in LFD so that results were better (p

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Summary Introduction The level of maximal lipid oxidation at exercise (LIPOXmax or FATmax) is exercise intensity, variable among individuals, at which a steady-state exercise performed over 45–60 minutes uses the greatest lipid/carbohydrate ratio and thus, minimises carbohydrate waste. This level has been demonstrated to be highly reproducible if tested in standardised conditions and is modified by a host of physiological or pathological situations. Whether it is stable over long periods of time remained unknown. Methods We had the possibility to measure this stability in a database of 1600 exercise calorimetries performed in our unit since 1998 and including several patients that did not modify their exercise or eating habits and were re-tested after a mean interval of 30 months. Patients (n = 11) represented a wide range of age (28–74 years), body mass index (22 to 46.7 kg/m2) and aerobic capacity. Results Their LIPOXmax ranged between a power of 18 to 123 watts and their maximal fat oxidation rate (MFO) ranged between 75 and 423 mg/min. There was a remarkable stability of the LIPOXmax expressed in crude power (r = 0.993, P Conclusion Therefore, the power at which lipid oxidation reaches a maximal during exercise remains stable over a mean period of 30 months if diet and exercise habits are not modified.

We recently proposed a unifying hypothesis to reconcile unexpected findings in exercise hemorheology and the classical concepts of “hemorheologic fitness” and the “triphasic effects of exercise”, based on the “healthy primitive lifestyle” paradigm. This paradigm assumes that evolution has selected genetic polymorphisms leading to insulin resistance as an adaptative strategy to cope with continuous low intensity physical activity and a special alimentation moderately high in protein, rich in low glycemic index carbohydrates, and poor in saturated fat. According to this protocol the true physiological picture would be that of an individual whose exercise and nutritional habits are close from this lifestyle, both sedentary subjects and trained athletes representing situations on the edge of this model. Unfortunately samples of people truly adhering to this ancestral lifestyle are hard to obtain. In order to address this picture we tried to compare databases obtained with our preceding published studies. As a model of the “healthy primitive lifestyle” we selected patients trained at low intensity (LI) and given an advice of protein intake around 1.2 g/kg/day. Results show a continuum for plasma viscosity which seems to be lower in athletes than LI-trained and even more sedentaries. When sedentary subjects become obese the most obvious characteristic is an increase in red blood cell (RBC) aggregation correlated to the size of fat stores. It is clear that 3 months of LI are not a perfect model of “healthy primitive lifestyle”, but these data suggest that the most important effect of LI regular exercise is to decrease plasma viscosity and that sedentarity increases RBC aggregation mostly when it results in increased fat storage.

Resume Introduction L’activite physique a un double effet sur le comportement alimentaire : un effet satietogene et un effet orexigene. Ce dernier semble favorise par la depletion glycogenique et semble donc s’observer davantage lors des exercices a haute intensite. La sommation de ces differents effets expliquerait pourquoi un meme exercice peut determiner une perte de poids importante ou au contraire une prise de poids. Notre hypothese est que l’efficacite du reentrainement au LIPOXmax s’expliquerait non seulement par un deficit energetique et une reprogrammation de l’utilisation des substrats au niveau du muscle, mais aussi en grande partie par une modulation du comportement alimentaire. Methodes et resultats Les effets aigus d’un exercice de 45 minutes cible au LIPOXmax par calorimetrie d’effort ont ete etudies lors de 62 seances d’induction de reentrainement au LIPOXmax realises chez des obeses (âge 22–77 ans, moyenne 51,46 ± 3,46). Le comportement alimentaire a ete teste avec l’echelle de Hill. Ce questionnaire montre que les effets de l’exercice realise au LIPOXmax sont de type anorexigene : au cours d’une seance, l’envie de manger reportee sur l’echelle analogique-numerique a diminue, que la seance soit realisee le matin (–2,82 ± 1,22) ou l’apres-midi (–3,05 ± 0,42). Conclusion L’horaire matinal ou vesperal de la seance ne modifie donc pas l’influence de ce type d’exercice sur le comportement alimentaire de sujets obeses : la tendance generale de cet effet, comme le montre une autre de nos etudes realisee sur 12 semaines, est bien de reduire l’appetit et la prise alimentaire.

Resume Introduction Nous rapportons l’observation d’un homme de 38 ans, maitre nageur et triathlete, traite depuis quatre ans pour maladie de Basedow ayant recidive a trois reprises. Il pratique 8 a 12 h de sport par semaine. Synthese des faits Le questionnaire SFMS retient une diminution de performance avec 35 items positifs sur 54, donc un score tres eleve. L’enquete dietetique denombre 3233 kcal/24 h dont 1,8 g/kg par jour de protides. Il pese 67,1 kg, dont 59,3 kg de masse maigre et 12 % de masse grasse. Un test d’effort triangulaire montre une VO2-max a 58,2 mL/min par kilogramme (147 % de la norme theorique) avec seuil ventilatoire a 55 % de cette VO2-max, mais avant son hyperthyroidie ces valeurs auraient ete 25 % plus elevees. En fait l’hyperthyroidie est parfaitement controlee selon les criteres usuels avec 25 mg/j de carbimazole, mais ce « parfait equilibre » est ressenti chez ce sportif comme comportant un etat de tachycardie relative qui le gene fortement dans sa pratique sportive et ses entrainements. Conclusion Cette observation montre que la normalisation d’une hyperthyroidie selon les criteres usuels laisse persister chez un sportif une hypersympathicotonie qui cree l’equivalent de la dysfonction sympathique de l’overreaching.

Resume Contexte Observation d’un jeune footballeur de 19 ans ayant du pratiquement stopper toute pratique sportive en raison de crampes et de myalgies s’etant peu a peu aggravees en 5 ans. Il est porteur heterozygote d’une mucoviscidose (mutation delta-F508), son frere homozygote realisant la forme symptomatique grave de la maladie. Methodes et resultats L’exploration neurologique, l’EMG et l’IRM des mollets, le doppler veineux des membres inferieurs n’apportent pas d’information. Le test d’effort montre une diminution de VO2max (37,5 mL/minute par kg, soit 81 % de la VO2max theorique) et du seuil ventilatoire (survenant a 43 % de la VO2max theorique). La biochimie a l’exercice ne montre pas d’anomalie caracterisee, tout au plus une reponse de lactate extremement marquee (atteignant 19,9 mmol/L) suivie d’une decroissance lente (constante γ2 du modele de Freund a 0,47 × 102/minute [N = 4 a 12]). Il n’y a pas de myoglobinurie et les rapports β-hydroxybutyrate sur acetoacetate et lactate/pyruvate sont normaux. Par contre, on note une hypokaliemie de depart a 3,3 mmol et dans les puissances elevees, l’ECG se modifie avec bascule transitoire de 170° vers la droite de l’axe de QRS sur le plan frontal. Conclusion Dans la mesure ou aucune autre explication claire de ces myalgies ne se dessine, on est tente de rattacher cette intolerance a l’effort avec hypokaliemie a un mecanisme comparable a celui decrit par M. Rodier chez des patients presentant la mutation L206 W, chez lesquels une perte sudorale de chlore exacerbee par l’exercice ou la chaleur entrainait un hyperaldosteronisme secondaire avec hypokaliemie responsable de crampes et de myalgies.

Summary Objective The objective was to assess the reliability of the crossover point (COP) and maximal fat oxidation (LIPOXmax) points in sedentary young men. Methods Maximal oxygen intake was assessed in 12 sedentary subjects (aged 20.5 ± 1.0 years), using a progressive maximal cycle ergometer test. They performed in random sequence, two submaximal graded exercise tests (E1 and E2), based on the measured maximal aerobic power (MAP) to test the reliability. The tests were separated by 4-day interval. Blood lactate, heart rate, respiratory parameters, the COP and the LIPOXmax points were measured during these submaximal exercises. Results We found no significant differences between E1 and E2 with respect to COP, LIPOXmax, and the corresponding heart rates. Coefficients of variation for COP and LIPOXmax values between E1 and E2 were low, falling well within the 10% criterion of absolute reliability. ICC measures of relative reliability were 0.96 for COP and 0.97 for LIPOXmax. The mean differences (bias) ± the 95% limits of agreement were 0.006 ± 0.066, –1.3 ± 12.15 W and 0.6 ± 7.1 W for the non-protein respiratory quotient (RER), COP and LIPOXmax, respectively. The smallest worthwhile changes for COP and LIPOXmax were 3.5 and 3.0%, respectively. The ventilatory threshold was significantly correlated to COP (r = 0.88, P Conclusion With appropriate care in establishing individualized submaximal protocol based on measured MAP, COP and LIPOXmax values have a good relative and absolute reliability in sedentary subjects, when they are retested over a 4-day interval. Moreover, during cycle ergometry, both of these indices are strongly correlated with the individual's ventilatory threshold.

Resume Introduction La technique de mesure de la composition corporelle par impedancemetrie bioelectrique (BIA) perd en precision en cas de maigreur ou de forte obesite, du fait des limites du modele mathematique cylindrique employe. La BIA segmentaire minimise cette cause d’erreur en modelisant le corps comme un assemblage de cinq cylindres. De nouveaux outils, dont l’utilisation est facilitee, permettraient de realiser les mesures de la composition des differents segments du corps afin d’etablir des correlations avec certains parametres metaboliques de facon plus aisee en pratique clinique en comparaison avec la DEXA. Synthese des faits Chez 36 sujets de 15 a 69 ans couvrant une plage d’Indice de Masse Corporelle (IMC) de 13 a 41 kg/m2 chez qui la composition corporelle est mesuree grâce a la DEXA en comparaison avec la BIA conventionnelle. La composition de chaque segment est precisement predite (r = 0,726 a 0,987), de meme que la masse grasse tronculaire (r = 0,9575 ; erreur moyenne 2,25 [95 %IC : 1,41–3,09]). Pour la masse grasse du corps entier la prediction est excellente (r2 = 0,9755 ; erreur moyenne 0,532[IC : –0,495–1,56]) et elle reste excellente chez les sujets maigres (r = 0,925 ; pente : 0,953, ordonnee 0,46 ; erreur moyenne 0,015 [IC : –1,1-1,13]). Chez 20 personnes explorees par petit dejeuner standardise avec modelisation mathematique, l’insulino-sensibilite determinee par l’oral minimal model (OMM-SI) s’avere davantage correlee a la MG tronculaire (r = –0,686) qu’a la MG totale ou a celle des membres. Conclusion L’approche segmentaire augmente la precision de la BIA conventionnelle y compris chez les sujets maigres.

Aim Online continuous glucose monitoring (CGM) during physical exercise would be highly useful in patients with insulin-treated diabetes. For this reason, this study assessed whether such a goal could be reached with a subcutaneous ‘needle-type' enzymatic sensor. Methods Ten patients (five women/five men), aged 51±12 years, with type 1 diabetes for 24±11 years treated by continuous subcutaneous insulin infusion (CSII) for more than 1 year (HbA 1c : 7.5±0.8%) performed a 30-min bout of exercise at a constant high-intensity load (15% above their individual ventilatory threshold) on a cycle ergometer. All patients wore a subcutaneous ‘needle-type' enzymatic glucose sensor linked to a portable monitor (Guardian ® RT, Medtronic-MiniMed, Northridge, CA, USA) that had been inserted the previous evening. Sensor calibration was performed against capillary blood glucose immediately before the exercise. CGM values were recorded every 5min from T –10 to T +30 , then every 10min during the recovery period from T +30 to T +90 . These recorded values were compared with blood glucose assays performed on simultaneously collected venous samples. Results Sensor functioning and tolerability raised no problems except for one sensor that could not be adequately calibrated. Data from this patient were excluded from the data analysis. An average blood glucose decrease of 63±63mg/dL (3.5±3.5mmol/L) (median decrease: 58mg/dL [3.22mmol/L]; range: –3mg/dL [0.16mmol/L] to 178mg/dL [9.8mmol/L]) occurred during exercise bouts, while CGM values decreased by 38±49mg/dL (2.11±2.72mmol/L) (median: 32mg/dL [1.7mmmol/L]; range: –15mg/dL [0.83mmol/L] to 58mg/dL [3.22mmol/L]). Cumulative paired glucose values ( n =135) could be analyzed. The correlation factor between CGM and blood glucose values was 0.957 with an intercept of 0.275. The mean difference between paired values according to Bland–Altman analysis was 10±31mg/dL (0.56±1.72mmol/L). Clarke error grid analysis showed 91% of paired points in A and B zones, while 0%, 9% and 0% of paired points were in the C, D and E zones, respectively. Conclusion Blood glucose changes during intensive physical-exercise bouts performed by CSII-treated type 1 diabetes patients can be estimated with acceptable clinical accuracy by online CGM.

Equations of blood viscosity provide a prediction of the 'optimal' hematocrit' (hct) as the hct resulting in the highest value of the bell-shaped curve of hematocrit/viscosity ratio h/η. We investigated if overweight and obesity have an influence on these parameters. We compared 32 normal weight subjects, 40 overweight (BMI 25-30) and 38 obese subjects. There was no difference in the theoretical curve of h/η. The actual h/η is the same in the 3 groups but is always higher than the theoretical h/η in all groups. The actual h/η is lower in overweight than controls (p = 0.011). Modeling yields the same value of theoretical optimal hct across BMI classes. The 3 groups have the same values of actual hct, but actual is significantly lower than optimal in all cases (p 0.001). Hematocrit is lower than predicted due to a discrepancy between predicted and actual h/η which is due to the inter-subject variability of RBC rigidity ... The discrepancy between optimal and actual h/η is negatively correlated to RBC rigidity indexes even if the model uses a fixed value of these indexes. Thus keeping in mind that the optimal hct should not be the same in the various parts of the vascular bed, its theoretical prediction with Quemada's equation appears to predict a value higher than actual hematocrit but well correlated to it, and the agreement between optimal and actual hct is dependent on RBC flexibility. This leads to think that the body sets hematocrit below its ideal value in sedentary subjects in order to cope with the need of increasing blood viscosity factors in case of exercise without impairing O2 supply to tissues.

International audience; Physiological studies on fetal blood in narrow glass tubes have suggested that fetal optimal hematocrit (hct) might be as high as 60%. A theoretical 'ideal' hct can also be predicted with a theoretical curve of hematocrit/viscosity (h/η) ratio vs hct constructed with Quemada's model. We used the database of one of our previous papers on fetal hemorheology to reinterpret its results with this concept. A series of 28 intrauterine cord punctures (between 19 and 33 weeks gestation) with doppler measurements of resistance in umbilical arteries was studied. The theoretical 'optimal hematocrit' was well correlated to actual (r = 0.857, p